A loud and powerful newspaper baron steps down under fire. What happens to the empire he built?

Conrad Black loves a good fight. The blustery press baron who owns the Chicago Sun-Times, Britain's Daily Telegraph and more than 140 other newspapers worldwide often writes letters to his own publications taking potshots at opponents. Two years ago, he even renounced his Canadian citizenship in a public battle with Prime Minister Jean Chretien in order to become a British peer, Lord Black of Crossharbour. As biographer Peter C. Newman put it, "He has the body language of a puma in heat."

But Black, 59, may not be quite so nimble as he thought. As he set out on a book...